A measurement device in the sense of the present disclosure is not to be understood as being restricted to a unitary collection of hardware components but can also be a system of spatially separated units. A measurement device can be viewed as including a transducer and a transmitter, wherein the transducer serves to convert a process variable, such as the fill level of a material in a tank, into an electrical signal, and wherein the transmitter serves to sample and process this electrical signal to produce a value for the process variable that corresponds to a physical situation that is to be measured. The transmitter, as the case may be, can further transmit and/or record the determined process value for further use. The transducer generally includes a microprocessor and/or microcontroller and various other electrical and electronic circuits. The transducer and the transmitter can be concentrated in a single unitary device, or they can be spatially separated. When they are spatially separated, some sort of communication pathway for the transmission of data and/or energy between the transducer and transmitter is provided, such as a cable or a wireless communications link, for example. The distinction between transmitter and transducer cannot always be strictly applied, as the transducer in some cases serves to preprocess a measurement signal and sometimes even comprises a microprocessor.
Fill level measurement devices with flexible wire probes are used to measure the fill level liquid materials in containers in applications where it is advantageous to concentrate the transmitted microwave energy so that signal losses can be avoided, and an improved sensitivity to the fill level can be attained. It is also possible to use flexible wire probes for capacitive fill level measurements.
Generally, fill level measurement devices that include a flexible wire probe will include also an end-weight for the flexible wire probe that positions the wire probe in a container. The probe is thereby put under a predetermined amount of tension and is oriented vertically. The tension applied to the flexible wire probe essentially eliminates any undesired bends or curves in the wire probe.
When a fill level measuring device includes more than one flexible wire probe, the probes are conventionally attached to a single end-weight to establish a defined end of the measuring range covered by the flexible wire probe.
However, to ensure each of the probes is subjected to a predetermined axial tensile force by the end-weight, the probes must be manufactured so that the lengths of the probes are essentially equal. This requires a high degree of manufacturing precision.
It would be possible to shorten one of the probes after installation as is disclosed for example in the German patent publication DE 000010009067 A1, wherein a measurement device having a cable probe is specified, and a method is given by which the cable probe can be shortened in a simple manner by an end user, wherein the adjustment is made on site and without the use of any special tools or other manufacturer-specific tools.
A further problem that can arise when two or more flexible wire probes are connected to the same end-weight is that flexible wire probes can be twisted such that when they are connected to the end-weight, they have an undesired rotational tension. This twisting can in some cases affect the length of the wire probe. When more than one flexible wire probe is attached to a single end-weight, there is no way for this rotational tension to be released, and in some cases this can inhibit the effectiveness of the end-weight in positioning the flexible wire probes in the container.